The present invention relates to fuel injection nozzles generally and more particularly to internal combustion engine fuel injection nozzles particularly useful with gas turbines. The nozzle assembly of the type to which the present invention relates includes a nozzle holder, a nozzle plunger and fuel-inlets with tangential ports, with the assembly being constructed to define a swirl chamber for the fuel within the nozzle assembly.
In known fuel-injection nozzles, there is provided a swirl chamber into which the fuel passes through tangential holes or slots. The fuel is formed in the swirl chamber into a vortex flow pattern having a generally fuel-free central or middle portion. The stream of fuel thus formed emerges from the nozzle in a form of hollow conical flow pattern.
When the fuels which are ordinarily used in operating gas turbines are utilized, it may occur that such fuels will contain corrosive constituents which could have a detrimental effect upon the turbine blades and the material of ducts through which hot gas is passed. For this reason, additives are normally mixed with the fuel in order to protect the components of the turbine. The additives are normally added to the fuel in the tank where the fuel is stored or, alternatively, additives may be mixed with the fuel during its flow through the fuel line which directs the fuel into the atomizing nozzle.
It has been found that certain additives are not compatible with foreign substances present in the fuel, an example of such substances being water. Since precipitation and deposits will occur in the fuel system, such precipitation or deposits may lead to blockages especially in components where relative sliding movements between closely fitting parts may occur, such as for example in valves, the fuel nozzle, control elements or the like.
Accordingly, it is an object to the present invention to provide a fuel-injection nozzle assembly which will permit the addition of appropriate fuel additives which may be fed to the fuel at a point where deposits of harmful substances will be avoided.
The principle aim of the present invention is to provide an assembly wherein the means supplying the fuel additives to the nozzle assembly are so arranged that the fuel supply and the additive supply are maintained separate from each other until a point at which the additive supply is introduced into the fuel flow at or near the swirl chamber of the nozzle assembly.